Telephone system



` E. s. PETERSON TELEPHONE SYS-TEM Filed NOV. 30, 1931 Y Aug. 1, 1933.

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ma Q Q J w mw d m uw. N\ Q\ ,I nw. 1 www: Qq w mNDOO f w A #mem @man Nm, ww f NN being Patented Aug. l, 1933 ingaan 'rELEPnoNs srsfrnm Edward S. Peterson, Elmwood Park, lil., assigner, by mesne assignments, to Associated Electric Laboratorieanc., Chicago, lll., a ilorp:nationl of Delaware Application November 30, 193i Serial No. 577,933

9 Claims.

The present invention relates in general to telephone systems, land more particularly to automatic telephone systems in which' access be had tor operators positions for information calls, call recording, or other similar services.

Trunks to speciall service operators are usually taken from the banks of selectors, such as special second selectors. In a large exchange there are a number of groups of these selectors and, in order to properly distribute the traffic, the trunks fromthe selector levels may terminate in rotary hunting switches which in turn have access in common to the special service trunks.

The main object-of the present invention is to provide a rotary hunting switch suitable for use onsuch special servicetrunks or in other cases where a similar hunting switch is required.

According to a particular feature of the invention, after the switch has been operated to select an idle trunk, it may be restarted to select a different idle trunk` by momentarily removing ground from the release trunk conductor of the seized trunk, and provision is made for the holding of the preceding switch train during the time that the .switch is re-operated to und a different idle trunk.

The above and other objects and features of the invention will best be understood from a perusal or" the following specification when read in connection with the accompanying drawing, comprising one figure only, which shows, by means oi he usual schematic diagram, only suilicient or" the apparatus in a telephone 'exchange to enable the present invention to be understood. Referring to the drawing, the lineswitch LS is mechanically similar to lthe well-known rotary lineswitch used in automatic telephony in which the wipers are advanced when the rotary inagnet is deenergized. The switch is ofthe socalled homing type, that is, the switch always returns to its normal or 'nome position after released. Lineswitches such as LS are access ble from selector levels, the `lineswitch LS being accessible over trunk conductors l, 2, and 3. [i number of these switches may be provided, all oi which havevaccess in common to trunks exi nding to special service operators positions, of which position No; l is shown somewhatV in detail and position No. 2 is indicated by the rectangle in the lower `portion of the drawing. A number of these operators positions may be provided depending upon the traiiic conditions. runks from the banks of the rotary lineswitches may be distributed to the several operators positions in sever l ways. For example, if there are three operators positions provided, the rst, fourth, seventh, etc., trunks may extend to the first operators position', while'the second, fifth, eighth, etc., trunks may extend to the second operators position, and the third, sixth, ninth, etc., trunks may extend to the third operators position.

Having given a brief description of the general layout, a detailed description ofthe operation of the disclosure will now be given.

For thispurpose it will be, assumed that a calling subscriber desires information and for this purpose has extended a connection through one or more selector switches to the trunk comprising conductors 1,' 2, and 3 and extending to the rotary hunting switch LS.

When, the trunk comprising conductors 1, 2, and 3 is seized by a selector switch and the subscribers loop is switched through, ground Yisv sent forward on release trunk conductor 2 at the saine time that a circuit is completed for line relay i extending from battery, upper winding of relay 4, resting contact of armature 18 and said armature, conductor 1, over the subscrbers loop, to conductor 3, armature 21' and its resting contact, lower winding of line relay 4 to ground. Relay 4 operates and at armature 6 and its working contact grounds the release trunk conductor 2 tohold the switching-through relay of the selector operated.

The release trunk conductor 2 now being grounded, a circuit for the stepping magnet 8 of the lineswitch LS may be traced overl th normally closed contacts controlled by armature 20, armature 14 and its restingcontact, nterrupter springs 9 of the rotarymagnet, winding oi rotary magnet 8 to battery. The rotary magnet 8 energizes in thisvcircuit and upon energizing opens its interruptor contacts 9. However, since contacts 7 are now closed, the interruptor contacts v9 are shunted and magnet 8 remains energized.

l-lhen line relay 4 energized, it also completed the circuit for slow-to-operate relay 10 at armature 5 and its working contact. Relay 10 operates after an interval and at armature 16 and its resting contact opens the shunt around interruptor spring 9, allowing the maghetto deenergize and advance the wipers or the switch one step. At armature 1l and its working contact relay lo connects ground to the lower winding of cut-off relay l'l, at armature 12 and its working contact it connects the junction point of the two windings of the cut-off relay to the test `mittently operatedto advance the switch wipersV CII .armature-s, it s v conductors,

connects wiper 2S, at armature 13 and its working contact it connects the rotary magnet to the test wiper 23 through the interruptor contacts 9 oi? the rotary magnet, at armature if: and. its rest" ing contact it opens the initialoperating circuit for the rotary magnet, at ar datore -15 `and its resting contact it opens tlie homing circuit of the switch.

Y The upper winding oi cut-o relay 17 is a ren sistance winding to prevent short-circuiting `or the battery and the relay will not energize over this winding. .Since the lower winding is short circuited as long asv test wiper `23 encounters a grounded bank contact, therelay does'not operate until wiper 23 fails to nd ground, This shunting circuit of the lower winding extends from ground on the bank Contact encountered by wiper 23, armature 19 and its resting contact,

armature 12 and its working contact, to the junction point ofthe two windings of relay 17. This saine ground also extends through armature 13 and its working contact, interrupter springs 9 of the rotary magnet, winding of rotary'rnagnet 8 to battery. As long as test wiper 23 encounters busy bank contacts, as indicated by ground. potential, rotary magnets is interstcp by vstepv in search of an idle trunk. In operating, rotary. 1lnagnet 8 `interrupts its own circuit at interruptercontacts 9 and, upon cleenergizing, itsteps the wipersto the `succeeding set of bank contacts and at the sarne time recloses its own circuit atits interrupter contacts.

1t will be assumed` that the trunk comprising conductors 32, 33, andfi extending to operators position No. 1 and accessible over bank contacts Z6, 27, and 28 is the irst idle trunk encountered bythe lincswitch LS. When the rotary magnet 8 deenergizes and steps the wipers 22, 23, and 25 into engagement with bank contacts 26, 27, and 28, there is no ground potential present on bank contact 27 engaged by vwiper 23 and, accordingly, the rotary magnet 8 `will not again energize. At this time the lower winding of cut-oil relay 17 is no longerY shunted by ground on the test wiper.

wiper 23.`

Line relay e deenergizesand, at armature 5 and its working contact, opens the circuit ci a lowacting relay 1Q; at the normally closed springs controlled by ar,.-iature 6, it closes a point in the homing circuit the switch; and, at armature 7 and its workingcontact, it opens a further'point in the shunting 9 of the rotary magnet.

of the core, and this also causes the relay to be somewhat slow -to releas 1t, therefore, maintains the ground on the of cut-ofi relay l17 'atarinature 11 its working contact for a short interval after line relay /1 has released. During this interval kground is sent baci: :Eroi/n the trunk circuit extending to the operators position over test wiper 23 to hold the cut-off vrelay 17 circuit of theinterrupter springs 1 The relay 10 is rnadeV slow' to operate by a slug on tlle armature end operated. A1li/hen relay 10 finally releases, it opens the initial energizing circuit of relay 17 at arma turell and working contact, at arrnatures 12 and 13 and their respective working contacts, it opensfthe testing circuit and operating circuits of the switchat arrnatiu'esle and l5 and their respective resting contacts, it completes points in the homing circuit of the switch, and, at arina= ture'16 and its resting contact, it again prepares the shunting circuit for the interruptor springs 9 of `the rotary magnet. v

When the cut-oir relay 17 of` 'the lineswitch LS "operated and switched through the subscribers loop overwipers 22 and 25 and bank contacts 25 and 28 to trunk conductorsBZ and 311, the line relay `17 of the trunk circuit operated from battery, upper winding of relay e7, upper left-hand winding of repeatinrt coil 50, conductor 32, bank contact 26 `and wiper 22, workingcontact oi armature 18 and said armature, conductor 1, subscribers loop, conductor 3, armature Z1 and. its working Contact, wiper and banircontact 28, conductor 34, lower left-liandwinding of repeatingcoil 50, lower winding of relay 47 to ground. Relay 47 operates this circuit and, atarniature 4S and its working contact, completes an obvious circuit for .the slow-to`releaserelay 4K1. At armature 49 and its working contact, it completes the circuit for the call lamp 5e extending from ground, armature '49 and its working contacf, resting contact o'armatu're 52 and said arria ture, lamp 5e to battery. Relay le operates and, at. armature and its'rworlring contact, extends ground from the contacts of the release key RK tothe testbank Contact 2'?, thereby busying this trunk in the banks or all ,the rotary lineswitc'nes having` access thereto and also providing a hold.- ing ground whichextendsfover wiper 23, armature 19 'and its working Contact, the two wind ings of relay 17 in series to battery. This ground is returned `troni the trunk Vcircuit'before the i slow-acting relay 10 has had time to release and open. the'circuit of the cut-oir relay 17, as previously mentioned.

The operator at position 1, upon noting the lighted condition lofthe la o 51and `being idle the time, operates her tening keyv K, thereby connecting the conductors 59 and 6i) extend-- ing to her telephone circuit through contacts 56 and 57 the listening leyrLK to the windings of the repeating` coil 59. operat on of key LK closes Contact 58, thereby enteng a circuit rom armature i6 i s working contact, contact 58 of lrey 131, winding of relay 51 to battery. Relay 5l operates vat arma ture 53 and. its working contact, locks itself operated to` ground at armature 16, and, at armature 52 and its resting contact, opens the circuit of lamp 551 thereby extinguishing the lamp.

The operator now converse with the cailingsubscriber and give him the desired iin-- formation.` lt the end of the conversation, she restores her listening key LK, thereby openingcontact 58,'but relay 51 is now locked energized to grounded armature 116, and the lanip 511 now lindenA the control ,of the calling su?,n scriber. Should the subscriber wish to recall the operator, he may operate his switch- 1nook several tiinc-s, thereby releasing and ren operati f `relay l17. Relay ell is slow to release and do not fall back during the momentary energizations of, relay e7. relay 17 .e leases,` it completes the circuit for the call lamp 5e at armature li9 l resting contact, therebyiiasliing the lamp to call to the attention oi CTI the operator that the calling subscriber Wishes to again converse.

When the calling subscribe* has obtained all the information he desires, he replaces his receiver, thereby opening the loop circuit extending to relay 47. Relay 47 releases and, at armature 49 and its resting contact, again completes' the circuiticr call lamp 54, but, vsincethe lamp remains steadily lighted at this time,l the operator knows that the subscriber is not signalling her. At armature 48 and its working contact, relay 47 opens the circuit for slow-to-release re lay Aitor an interval, relay 44 releases and, at armature 46 and its 'working contact, opens the locking circuit or" relay 51 to allow this relay to release. Relay 51 releases and, at armature 52 and its working contact, opens thev circuit of the call lamp 54, thereby extinguishing this lamp. At armature and its working Contact, relay 44 removes ground from test bank Contact 27, thereby allowing cutoi relay17 or the lineswitch 'LS to release.

At armatures 18 and 21 and their respective resting contacts, relay 17 again extends the trunk conductors 1 and 3 to the .windings of line relay 4, but this relay does `not operate at this time, since the calling loop is open. At armature 19 and its resting contact, relay 17 again prepares the testing and operating circuits of the lineswitch, and at armature 20 it removes ground conductor 2 and at the normally closed 's controlled by armature 29 it completes homing circuit of the switch extending from grounded Yoanlr contacts engaged by wiper resting contact vof varmature 15 and said armature, normally closed springs controlled hy armature 6 of relay 4, normally closed springs controlled by armature 20 of relay 17, armature 14 and its restingccntact, interruptor contacts oi the rotary magnet, winding of rotary magnet to battery. A

Rotary magnet 8 energize-s and,`at"interrupter contacts .1, interrupts vits own circuit, thereby allowing it to deenergize and advance the Wipers one step. The wiper 24 encounters grounded banl; contacts until the switch 'has reached its normal position, and, therefore, rotary magnet 8 continuesto operate to step the wipers until ground is noV longer present on the bank contact encountered by Winer 24. During the' hoining operation 'of the switch the release trunk. conductor Eis grounded from the ground on the sank contact encountered 'oy wiper 24 to maine tain the lineswitch LS busy to selectors' having access thereto. When the wipers ci the switch reach their normal position, wiper 24 no longer finds ground potential, and the rotary magnet 8 remains deenergized. Groundl is also removed from release trunk conductor 2, thereby rendering switch` LS available to selectors. All oi the app ratus used in the establishment of the call. to the operator has now been restoredto normal.'

1t will now ce assumed that, when the lineswitch LS has been seized and has operated to the trunk line comprising conductors 32, 3, and extending to operators position No. 1

wel:

and the call lamp 54 has been operated 'at this y Vlineayitch LS is now in'hunting condition deenergizes for the `rst bank contact 27, Athereby removing ground from the windings of the cut-oli relay 17 of lineswitch LS. This relay accordingly releases and,

Vat armatures 18 21 and their respective resting contacts, again extends the'calling loop to the `windings or" line relay 4. At armature 2O and its Working contact it removes one ground connection from the release trunk conductor 2,

but this conductor remains grounded from the homing wiper 24 over he resting contact or arrn ature 15 and said armature, and the normally closed contacts controlled by armature 6. At the normally closed springs controlled oy armature 20,'a circuit is completed iro-in ground on the homing wiper 24, resting contact o armature 15 and said armature,normally closedsprings controlled by arm 5', normally closed springs controlled by andature 20, armature 14 and its estingcontact, interruptor springs 9 of the rotary magnet, windinT oi rotary magnet 8 to hattery. The rotary" magnet 8 ene zes in this circuit, but in the .meantime the line relay has energized and, at armature 6 and its working contact, has placed direct ground on release trunk conductor 2 and on the above-traced oseru Thus, `when the rotary magnetenergiaes and opens itsv interrupter springs, it does not innnev diately release lout is held operated over this shunting path.

Line relay 4, in its working contact completes an obvious circuit for the slow-to-operate.. relay 1G. rP .elay 1G op-- eratcs after interval and, at ar-nature 12 and its working contact, again completes the test cir cuit rornwiper 2,3 to the junction point or" the windings oi cut-ofx` relay i7. At armature operating, at armature 5 and and its resting contact, it opens the shunt around interrupter springs 9 and, vsince the springs are now open, the circuit to rotary magnet l is opened, and the magnet deenergizes to advance the switch v ipers to the ncrv, set oi hanlrcontacts.V At armature ll and its rf i Le:

hunts for an idle trunl; to one the other operators positions. vSince the trunks iollcwing the one accessible inhanl; 26, 2

and 2S go to the other operators ons inV turn, the lincswitch LS will. s :ze one o.. these to advance the switch wipers from contacts 26, 27, and

cut-od relay 17 immediately operates and, at

armatures 18 21 and their respective working contacts, disconnects the line relay 4 and,

ne ccntac'aarmature 13 switches through the subscrihers loop to. operators position No. ,2 over trunk. conductor 37. The remainder ci the operation the saine as that previously described in connection with the completed call: over trunl; conductors 33, and 34. What is claimed is: 1. In a telephone system, va rotary hunting switch accessible from a preceding-selector, av 'plurality of trunks accessible to said switch and operators'positiomand means in said switch'forV holding the preceding selector operated during the time said switch-is selecting said second idle trunk.

l 2. In a telephone system, a plurality of trunk circuits, a `hunting switch accessible to a preceding selectork and having access to said trunk circuits, means responsive to theseizure, of said switch by the preceding selector for operating it to selectv an idle one of said trunk circuits, a holding circuit for said switch completed by the seized trunk circuit,'means responsive to the opening of said holding circuit for causingl said switch'to select a different idle one oi said'trunl:l circuits, and means in said switch for maintain- .ing the preceding selector operated during the said different idleV slow-acting relay Yfor opening the-shunt around said` interrupter contacts, for opening the initial time saidl switch is selecting one of said trunk circuits. v

3. In a telephone system, a plurality of trunk circuits, a hunting switch having access to said trunk circuits, a trunk "incomingV to said switch including a holding conductor, a means responsive to the seizure of said switch over said incorning trunk for operatingit to seize an idle one of said trunk circuits,rme`ans in the seized trunk circuit for causingV said switch Yto reoperate to .seize` different idle trunk circuit, and means in said switch ior maintaining holding potential Yon said incoming holding conductor during such reoperation.

4. In a telephone system, `a` `plurality of trunk circuits, a hunting switch having access thereto,

atrunk. incoming to said switch including a holdingv conductor-,'ineans responsive to the seizure of said switch over said incoming trunk for, placingY holding potentialon said incoming holding conductor and for operating saidswitch to seize an idle one of said trunk circuits, a holding circuit ior said switch completed by the seized trunk circuit, means in said trunk circuit for opening said holding circuit, means responsiveto said last means for causing the switch to'select a different idle trunk circuit, and means Vformaintaining kholding potential on said incoming holding con- -the'switch to select an idle one of said trunk` lines, means in said switch for returning ground operator at said position in case she is too 'at the working contacts of these armatures,

potential` over said incoming holding conductor to hold preceding switches operated, a test wiper in. said switch grounded by the seized trunk line to hold saidswitch operated, means responsive to the removal of ground from said test wiper for operating said switch to select the next idle trunk line, means lresponsive to the release of said incoming trunk for` returning said switch to its normal position, and means in said switch for maintaining a continuous ground potential on said incoming holding conductor until said switch has returned to its normal position.

6. In a homing type rotary lineswitch, ,an incoming trunlrincluding a holding conductor, a

' plurality of trunk lines accessible to said switch,

means responsive to the seizure of said switch over said incoming trunk for operating it to select an idle one oi said trunk lines, means in the selected trunk line for causing said switch to select a different idle trunk line, means responsive `to the release of said incoming trunk for returning said switch to its normal position, and means for maintaininga continuous ground potential on said incoming holding conductor from the instant theswitch is seized until it returns to its normal position.

7. In a rotary hunting switch, a line relay, a slow-acting relay, and a cut-ofi relay, an operating magnet having interrupter contacts, means responsive tothe operation of said line relay when said switch. is seized for completing a circuit for said slow-acting, relay, for completing a circuit for said magnet through said interruptor contacts, and for shunting said interruptor contacts to hold said magnet energized, a test wiper, andmeans responsive to the'operation of said energizing circuit ofsaid magnet, for Vextending ar self-interrupting circuitior said magnet to said test wiper, for completing a circuit for said cut-oif'relay, and for extending a shunting circuit for said cut-ofi relay to said test wiper.

In a hunting-switch, a line relay, a slowacting relay, a circuit for said slow-acting relay controlled hy line relay, a rotary magnet having interrupter springs, an operating circuit for lsaid magnet including said interruptor springs, means responsive to the seizure of said switch for closing the operating circuit for said magnet'and for operating said line relay, con-,r

said shunt when said relay operates.

' 9. In a rotary hunting switch, a line relay and a slow-acting'relay,' a circuit for said slow-acting ,relay controlled by said line relay, a magnet having interrupts' springsan. operatin T circuit for said f magnet i including said interruptor springs, responsive tothe seizure of said switch `for completing the operating circuit to said magnet and for energizing said line relay, contacts on said line relay ,for shunting said interruptervsprings to `hold said magnet* energized, a test wiper, and contacts on said slow-acting relay for opening said shunting circuit, lfor opening the initial operating circuit of said magnet,

and lor extending a` circuit for said magnet to M 

